Tuberculosis (TB) in children most commonly results from exposure to a household contact with active TB, and represents ongoing transmission of Mycobacterium Tuberculosis (Mtb) in the community.

Infants and young children have an increased risk of infection following exposure and progress more readily from infection to active TB disease; in the absence of intervention, infants have a 50-60% risk of disease in the first year following infection. It could therefore be argued that the determining factor for the higher susceptibility to disease in children is prolonged, intimate contact between the child and the index case, which might lead to a larger inoculum of Mtb. However, there is little evidence to support this assumption, since the mycobacterial load in children is notoriously low, whi...